Ritonavir is an antiviral medicine that prevents human immunodeficiency virus (HIV) from multiplying in your body.

Ritonavir is used together with other antiviral medicines to treat HIV, the virus that can cause acquired immunodeficiency syndrome (AIDS). Ritonavir is not a cure for HIV or AIDS.

Ritonavir may also be used for purposes not listed in this medication guide.

Tell your doctor about all your other medicines. Some drugs should not be used with ritonavir.

Ritonavir comes as a capsule, a tablet, and a solution (liquid) to take by mouth. It is usually taken twice a day with meals. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take ritonavir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Your doctor will probably start you on a low dose of ritonavir and gradually increase your dose, not more often than once every 2 to 3 days. Follow these directions carefully.

Swallow ritonavir tablets whole. Do not split, chew, or crush them.

If you are taking the oral solution, use a dose measuring spoon, syringe, or cup to measure the correct amount of liquid needed for each dose. Do not use a regular household spoon. You may take the solution by itself, or you may improve the taste by mixing it with 8 ounces of chocolate milk or Ensure or Advera brand dietary supplements. If you mix the medication with one of these liquids, you must drink the mixture no longer than 1 hour after you mix it.

If your doctor tells you to stop taking ritonavir capsules and start taking the tablets instead, you may experience more side effects such as nausea, vomiting, stomach pain, and diarrhea shortly after you switch. These symptoms may improve as your body adjusts to the tablets.

Continue to take ritonavir even if you feel well. Do not stop taking ritonavir without talking to your doctor. If you miss doses, take less than the prescribed dose, or stop taking ritonavir, your condition may become more difficult to treat.

Ritonavir should not be used without other antiviral medication. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Take with meals.

Read and follow all Instructions for Use. Ask your doctor or pharmacist if you need help.

Swallow the tablet whole and do not crush, chew, or break it.

Shake the oral solution (liquid). Measure a dose with the supplied syringe or a dose-measuring device (not a kitchen spoon).

Follow your doctor's dosing instructions very carefully when giving ritonavir to an infant. Doses are based on body surface area (height and weight) in children. The dose may change if the child grows or gains weight.

Use all HIV medications as directed. Do not change your dose or stop using a medicine without your doctor's advice. Remain under the care of a doctor.

You will need frequent medical tests.

If you've had hepatitis B, it may come back or get worse. You may need liver function tests while using ritonavir and for several months after you stop.

Store the tablets, liquid, or powder at room temperature away from heat or moisture. Do not refrigerate. Keep tightly closed when not in use.

Store the capsules in the refrigerator or at room temperature away from moisture, heat, and light. Or store at room temperature and use the capsules within 30 days.

Some drugs should not be used with ritonavir. Your treatment plan may change if you also use:

• alfuzosin, apalutamide, cisapride, colchicine, St. John's wort, voriconazole;

• sildenafil (Revatio) when used to treat pulmonary arterial hypertension (PAH);

• antipsychotic medicine--lurasidone, pimozide;

• cholesterol-lowering medicine--lovastatin, simvastatin, lomitapide;

• ergot medicine--dihydroergotamine, ergotamine, methylergonovine;

• heart medicine--amiodarone, dronedarone, flecainide, propafenone, quinidine, ranolazine; or

• a sedative--oral midazolam or triazolam.

Tell your doctor if you have ever had:

• liver disease (especially hepatitis B or C);

• heart problems;

• diabetes; or

• a bleeding disorder such as hemophilia.

Ritonavir liquid contains alcohol and propylene glycol, and should not be used by pregnant women or premature babies.

To prevent HIV in a newborn baby, use all medications to control your infection during pregnancy. Your name may be listed on an antiviral pregnancy registry.

Ritonavir can make birth control pills or skin patches less effective. Ask your doctor about other birth control options such as an injection, implant, vaginal ring, condom, diaphragm, cervical cap, or contraceptive sponge.

Women with HIV should not breastfeed. The virus can pass to your baby in your breast milk.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Get your prescription refilled before you run out of medicine completely.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of ritonavir oral liquid could be fatal to a child.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store the tablets and solution at room temperature. Do not refrigerate the solution and do not let it get too hot or too cold. It is best to refrigerate ritonavir capsules, but you may also store them at room temperature for up to 30 days.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

Unless your doctor tells otherwise, continue your normal diet.

Drinking alcohol or taking disulfiram (Antabuse) while taking ritonavir capsules or liquid may cause unpleasant side effects.

Using ritonavir will not prevent your disease from spreading. Do not have unprotected sex or share razors or toothbrushes. Ask your doctor how to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe.

Get emergency medical help if you have signs of an allergic reaction (hives, skin sores, difficult breathing, fast or pounding heartbeats, sweating, mouth sores, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Ritonavir may cause serious side effects. Call your doctor at once if you have:

• irregular heartbeats, or a light-headed feeling (like you might pass out);

• easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

• signs of a kidney stone--pain in your side or lower back, blood in your urine, painful or difficult urination;

• high blood sugar--increased thirst, increased urination, hunger, dry mouth, fruity breath odor; or

• signs of liver or pancreas problems--loss of appetite, upper stomach pain (that may spread to your back), nausea, vomiting, dark urine, jaundice (yellowing of the skin or eyes).

Ritonavir affects your immune system, which may cause certain side effects (even weeks or months after you've taken ritonavir). Tell your doctor if you have:

• signs of a new infection--fever, night sweats, swollen glands, cold sores, cough, wheezing, diarrhea, weight loss;

• trouble speaking or swallowing, problems with balance or eye movement, weakness or prickly feeling; or

• swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence.

Common side effects of ritonavir may include:

• nausea, vomiting, stomach pain, diarrhea;

• numbness or tingling in your hands or feet or around your mouth;

• feeling weak or tired;

• rash; or

• changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and waist).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Sometimes it is not safe to use certain medicines at the same time. Some drugs can affect your blood levels of other drugs you use, which may increase side effects or make the medicines less effective.

Many drugs can affect ritonavir, and some drugs should not be used at the same time. Tell your doctor about all other medicines you use. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to ritonavir.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.